Telephonic receiver.



A. MARR.

TELEPHONIG RECEIVER.

APPLICATION FILED JAN. 8, 1913.

1,087,127. Patented Feb. 17, 1914.

' I I fkl/az/ JMUW WW ALEXANDER Mam, or MANCHESTER, ENGLAND.

TELEPHONIC RECEIVER.

Specification of Letters Patent.

Application filed January 8, 1918. Serial No. 740,836.

To all whom it may concern Be it known that I; ALEXANDER MARK, a

subject of the King of Great Britain and Ireland, and a resident ofManchester, England, have invented new and useful Improvements inTelephonic Receivers, of which the following is a specification.

In a type of telephonic receiver al eady known the end of the magnetpole an the rim or the like of the body of the receiver which forms aseat for the diaphragm, are so relatively disposed and arranged thatwhen the diaphragm is laid upon its seat its center is pulled down on toand in Contact with the magnet. The diaphragm thus assumes a shallowcupped or dished form. This pulling down or dishing of the dia phragmresults in a slight upturning of the periphery of the diaphragm from itsseat.

W hen the cap of the instrument is screwed down and reaches thediaphragm, the slightly upturned periphery of the diaphragm is firstpressed down by the cap, and this pressing down of the diaphragmperiphery results in a flattening of the diaphragm and the elevation ofits center from and out of contact with the magnet end. The furthermovement of the cap results in the opposite faces of the diaphragmadjacent to the periphery being tightly clamped between opposed flatfaces on the seat and on the inner face of thecap. The diaphragm, beinglifted from the magnet, can vibrate under magnetic variations andundulations but the greatest possible freedom of vibration is notattained because of the described clamping of opposite faces of 'thediaphragm.

The object of my invention is to so mount the diaphragm and to so formand relatively combine the body of the receiver and the cap that thediaphragm cannot be clamped between oppositely disposed parts of them.When a receiver body, cap, and diaphragm are combined according to myinvention for use the diaphragm is only supported on its inner face orface nearer to the magnet by a circular line some distance from itsperiphery and on its outer face by a concentric circular line of largerdiameter.

' With this arrangement very great freedom of vibration of the diaphragmis permitted and an instrument of very much greater sensitivity isobtained than with a diaphragm the opposed faces of which are oppositelyclamped in the usual manner.

seats E and A.

The accompanying drawings illustrate various improved forms of diaphragmmount ing, the curvature and thickness of the diaphragm and theformationand dimensions of the parts and spaces which insure the diaphragm beingproperly held being exaggerated to more clearly show this invention.

Figure 1 is a sectional view of part ofa receiver and itsv cap anddiaphragm, showing the latter pulled down and in contact with the end ofthe magnet. Fig. 2 is a similar view of the same parts but with thediaphragm lifted out of contact with the -magnet and held according tothis invention. Figs. 3 and 4 are like sectional views illustratingvarious modifications in the parts by which the diaphragm is held.

Similar parts are indicated by like letters of reference where theyoccur in the differ-.

ent drawings.

Referring first to Fig. 1, A represents the body of the receiver whichmay be formed with the usual seat A for the diaphragm B. O is themagnet. When the diaphragm D is laid in place upon the seat A the pullof the magnet pulls down the center of the diaphragm until it touchesthe magnet. Owing to the curvature thus given to the diaphragm itsperiphery projects upward from the seat A. When the cap E is screwedPatented Feb. 17, 1914.

in place it reaches the positionshown in Fig. 1 without its seat or flatface E reaching or exerting any pressure on the periphery of thediaphragm. Upon being screwed farther down than as shown in Fig. 1, theface E comes down upon the periphery of the diaphragm and by pressing itdownward toward the seat A slightly reduces its concavity and lifts thediaphragm away from and free of the magnet as shown in Fig. 2.

As soon as this has occurred the shoulder or the like F on the innerface of the cap comes down solidly upon the seat A and I preventsfurther downward movement of the cap and prevents the opposed faces ofthe diaphragm being clam ed between the The shou der F is of such adepth that although it permits the face E to come upon the diaphragm andlift it from the magnet, it insures that a recess or space shall be leftbetween the face E and the seat A which shall be of slightly greaterdepth than the thickness of the diaphragm. \Vith such an arrangement theunder face of the diaphragm is only supported along the sharp line ofthe inner periphery of the;

seat A and the upper or outer face is only supported by the sharp edgeof the periphcry .of that face coming againstt e seat E of the cap. SeeFig. 2. In Fig. 3 the same result is shown as being attained by forminga slight recess G in the brass cup of a Western electric type ofinstrument. This recess is of slightly greater depth than the thicknessof the diaphragm and its wall F thus prevents the ca E being screweddown sufficiently far to c amp opposite parts of the diaphragm betweenitself and the receiver body. Fig. 4 illustrates a like recess G for thereception of :1 dia. hragm turned in the end of a receiver of l i e typeto that shown in Figs. 1 and 2.

What I claim is A telephonic receiver comprising a body,

greater depth than the thic 'ness 0 cap and diaphra the ca havin ashoulder 'which sc gws down solidly u on the end of the body, and arecess bein eft between the adjacent edge portions 0 the cap and body toreceive the ed e of the diaphragm, such recess bein 0 sli htllly t ediaphragm so that when the cap is screwed down home the dia hragm isjust clicked oil the magnet an opposite parts of it are not clamped.

In witness whereof Ihave hereunto set my hand in the presence of twosubscribing witnesses.

- ALEXANDER MARR.

Witnesses:

WILLIAM G20. Hays, JOHN OCoNNEpL.

